Systems Thinking
Systems thinking means to design every aspect of the house together, because doing so often involved either tradeoffs or synergies. We start by asking how the building will actually be used by understanding human behavior, not how it is conceptually or traditionally used. We build only those spaces that are actually regularly used and look for ways we can use rooms for multiple functions, all while trying for some flexibility in lifestyles. We also accept that different family have different requirements and don't try to make a "one size fits all" solution.
Once we know what we need, we examine the climate of the building site and design with it in mind, taking advantage of solar energy, shading and natural cooling. Given these constraints we design so that materials, energy and water are used efficiently over the lifetime of the building. Finally in each decision, we give consideration to what will become of the house when its lifetime is over.
When we are done we have a building that works with its environment, rather than against it; has minimized its impact on the planet in some way; its healthier for it occupants and is designed to "feel good".
In systems thinking we often find synergies: for example by taking advantage of solar energy and super-insulating, we can dramatically downsize the size of our heating and cooling equipment, resulting in little or no up-front costs AND reduced operating costs. These kinds of possibilities are often limited more by not looking for them, than being hard to do.